Algorithm - a process for completing a task. An encryption algorithm is merely the process, usually a mathematical process, to encrypt and decrypt messages.

Asymmetric Key Cipher - Also known as public-private key cryptography system

Authentication - the process of verifying that a file or message has not been altered in route from the distributor to the recipient(s).

Back Door - an alternate, usually secret, method to decrypt an encrypted file or message. This method is usually only known to a few people, such as the author of the program. The presence of a back door greatly reduces the reliability of the implementation of an encryption algorithm.

Cipher - a cryptographic algorithm used to encrypt and decrypt files and messages.

Ciphertext - the disguised (or encrypted) file or message.

Code - the usage of characters or words to represent words, sentences, or ideas. Morse code is a common example, where combinations of dots and dashes represent letters and numbers.

Cryptanalysis - the art of breaking cryptosystems. The process of looking for errors or weaknesses in the implementation of an algorithm or of the algorithm itself.

Cryptography - the art of creating and using cryptosystems.

Cryptology - the study of both cryptography and cryptanalysis.

Cryptosystem - the entire process of using cryptography. This includes the actions of encrypting and decrypting a file or message, or authenticating the sender of an e-mail message.

Decryption - any process to convert ciphertext back into plaintext.

DES - Data Encryption Standard. A cipher developed by the United States government in the 1970s to be the official encryption algorithm of the U.S.

Digital Signature - systems allow people and organizations to electronically certify such features as their identity, their ability to pay, or the authenticity of an electronic document. More information available at http://www.cdt.org/digsig/

Encryption - any process to convert plaintext into ciphertext.

Key - a collection of bits, usually stored in a file, which is used to encrypt or decrypt a message.

Key Escrow - a process that requires a copy of all decryption keys be placed into escrow so that encrypted messages may be decrypted as required by a law enforcement agency.

Law Enforcement Agency - any group that has the legal authority to enforce the laws of a political body. This includes local or state police, Federal Bureau of Investigations (FBI), and the Central Intelligence Agency (CIA).

Passphrase - similar to a password but can be made up of any number of characters. A passphrase is generally thought to be stronger than a password, although not many programs support the use of a passphrase.

Password - a group of characters that is used to access something, such as checking e-mail. A password is usually between 3 and 10 characters in length.

PGP - Pretty Good Privacy. A public-private key cryptography system which allows for users to more easily integrate the use of encryption in their daily tasks, such as electronic mail protection and authentication, and protecting files stored on a computer. PGP is available for free to individual home users.

Plaintext - the original message or file. After a file or message has been encrypted and then decrypted you should end up with the original file or message.

Private Key - the secret key of a public-private key cryptography system. This key is used to "sign" outgoing messages, and is used to decrypt incoming messages.

Public Key - the public key of a public-private key cryptography system. This key is used to confirm "signatures" on incoming messages or to encrypt a file or message so that only the holder of the private key can decrypt the file or message.

Public-private Key Cryptography System - a cryptography system that uses two different keys to lock and unlock (encrypt and decrypt) messages and files. The two keys are mathematically linked together. An individual's public key is distributed to other users and is used to encrypt messages to the individual. The individual keeps the private key secret and uses it to decrypt messages sent with the public key.

Steganography - the process of hiding data inside other data. For example, a text file could be hidden "inside" an image or a sound file. By looking at the image, or listening to the sound, you would not know that there is extra information present.

Symmetric Key - the key that is used to encrypt a file or message is the same key that is used to decrypt the file or message.

TripleDES - A method of improving the strength of the DES algorithm by using it three times in sequence with different keys.